The defects occurring on the backside of the wafer take 10% of the basic yield loss of the wafer fab. The backside defect may have a significant impact on the uniformity of the wafer and process, and the wafer backside could be contaminated or damaged in all processing steps including deposition, etching, and CMP.
Such defects result in tens of millions of dollars of loss annually, so the manufacturer must proceed with the automated non-destructive wafer backside inspection as an essential step of all processes in order to restore the loss.
The wafer backside inspection equipment applies the 2D optical system and vision algorithm to inspect any scratches and particles on the backside of the wafer.